1. Field of the Invention
This invention relates to a carbon nano-fibrous rod (carbon nanorod), fibrous nanocarbon, and a method and apparatus for producing fibrous nanocarbon.
2. Description of the Related Art
In recent years, a carbon nanofiber (in 1983, United States of America, Hyperion Catalytic International, Japanese Patent Application Laid-Open No. 1987-5000943, Multi-walled Nanotube, The number of walls varies, with 8 to 15 being typical. The outside diameter of the tube is approximately 10 to 15 nanometers. The inside diameter is approximately 5 nanometers. Nanotubes are typically tens of microns in length. Aspect ratios on the order of 100 to 1000), (H. P. Boehm, Carbon, 11, 583 (1973), H. Murayama, T. Maeda, Nature, 245, 791, Rodriguez, N. M. 1993. J. Mater. Res. 8:3233), and carbon nanotube (S. Iijima, Nature, 354, 56 (1991), S. Iijima), for example, have been discovered as carbon materials on the order of nanometers (nm=one-billionth of a meter). These materials have attracted attention as fine carbon materials. Outlines of the structures of conventional carbon nanofibers are shown in FIGS. 49(a) to 49(c). In the conventional carbon nanofibers, three types of structures comprising a stack of plate-shaped hexagonal carbon layers have been proposed as shown in FIG. 49 (Rodriguez, N. M. 1993, J. Mater. Res. 8:3233). These carbon materials have been classified into a platelet structure in FIG. 49(a), a herringbone or fishbone structure in FIG. 49(b), and a tubular, ribbon or parallel structure in FIG. 49(c), as their three-dimensional structures. However, the conventional carbon nanofibers have no diversity because of their prescribed simple structures, and have not served as materials which fulfill diverse functions at the same time.
In recent years, application studies using carbon nanofibers have been conducted. For example, these studies cover occlusion or adsorption and desorption of hydrogen and lithium, catalytic action, and adsorption of nitrogen oxides. A high capacity of occluding target substances is required of carbon nanofibers for such uses, but preferred carbon nanofibers have not appeared yet.
Thus, there is a strong demand for the advent of fibrous nanocarbon substances which can impart a variety of characteristics at the same time by variously arranging or gathering carbon nano-fibrous rods of diverse dimensions and shapes so as to systematically prepare a fibrous nanocarbon having a wide variety of structures.
In the production of a carbon nanofiber, a basic reactor, as shown in FIG. 50, is utilized. As shown in FIG. 50, a conventional basic reactor is of a batch type in which a source gas 01, as a carbon source, is brought into contact with a catalyst 05 placed on a boat 04 within a reaction tube 03 provided with a heating means 02, whereby a carbon nanofiber 06 is grown on the catalyst 05. The conventional apparatus, as shown in FIG. 50, therefore, has posed the problem that mass production cannot be performed.
Hence, as shown in FIG. 51, for example, a vapor phase flow process for producing carbon nanofibers has been considered. In the vapor phase flow process, a source gas 01 is heated by a heating means 02, while being supplied into a reaction tube 03, to produce a carbon nanofiber.
However, with the basic reactor shown in FIG. 50 or the vapor phase flow process as shown in FIG. 51, the problem occurs that the interior of the reaction tube 03 tends to cause a temperature distribution and a non-uniform temperature. There is also the problem that the grown product is prone to deposit on the inner wall surface of the reaction tube 03, making it difficult to recover the product. This presents the problem that the production on an increased scale is difficult.
In the light of above-described circumstances, it is an object of the present invention to provide a carbon nano-fibrous rod which can show a high potential in the occlusion or adsorption and desorption of hydrogen and lithium, catalytic action, and adsorption of nitrogen oxides. In particular, the present invention includes a fibrous nanocarbon comprising carbon nano-fibrous rods which are arranged and gathered, and a method and apparatus for producing the fibrous nanocarbon.